116 Proveedings of the Royal Physical Society. 
correctly identified by Whiteaves (op. cit., pl. ix., fig. 3). 
Now attached to the antero-external margin of this plate 
is seen the spine-like body recently described by Mr Smith 
Phlyctenaspis Acadica, Whiteaves; restoration of ventral carapace, a.v.l., 
anterior ventro-lateral plates; p.v.J., posterior ventro-lateral, not defined 
in the outer margin in the fossil; @.m.v., anterior median ventral; im.v., 
median ventral; 7./., interlateral; c., cornu or lateral spine. 
Woodward. ‘This spine occurs not only in the specimen on 
which the above restored sketch is founded, but in the 
collection now before me is found both absolutely detached, 
and also in articulation with otherwise isolated examples 
of the anterior ventro-lateral plate. 
Mr Woodward mentions these spines as “each apposed 
to a lateral plate of the trunk”: it is now shown to which 
lateral plate, as well as to which part of the dermal armour 
of Coccosteus, they correspond. 
It will be seen that the spine (c.) touches with its proximal 
extremity a narrow portion of bone (2./.), which is articulated 
with the anterior margin of the anterior ventro-lateral plate 
(avJ.). On turning to my previous restoration of the ventral 
cuirass of Coccosteus decipiens, Ag.,! it will at once be seen 
that this portion of bone corresponds exactly to the anterior- 
inferior part of the interlateral plate (7./.), which occupies the 
same position with regard to the anterior ventro-lateral, 
and meets its fellow of the opposite side in front of the 
anterior median ventral (a.m.v.), while the spine, in like 
manner, corresponds to the short process which passes 
' ' Ann, and Mag, Nat. Hist. (6), vol. v., 1890, pl. x., fig. 3. 
